D4 coolant loss

[monkeyboyuk]

unexplained loss of coolant twice now since I bought car. i just put the first instance down to the imbecile garage mechanics.....

however it happened again, just as random, no visible signs of any leaks, no overheating, nothing funky under the oil cap, no smells of antifreeze etc.....

what else should I be looking for..?

[steamship]

I'd suggest getting some UV dye added to the coolant and checking over the entire engine after its been for a run to see if there is an obvious leak. Looking through some other forums, they mention a few possible options like water pump, oil cooler, EGR cooler and coolant leaks in and around the V of the engine. There is also the following thread on here, with post #2 interesting:

http://forum.a8parts.co.uk/showthread.php?t=15736

[monkeyboyuk]

Thanks, it had new water pump decemberish iirc

Think I’d read that post already when I’d been mooching round before posting

Should add as well it seems to be when I’ve laid the car up a couple days, like over weekend and maybe not been out in it that it all of a sudden alarms me to the loss….. and it’s drained to well below the minimum

[steamship]

Originally Posted by monkeyboyuk

Should add as well it seems to be when I’ve laid the car up a couple days, like over weekend and maybe not been out in it that it all of a sudden alarms me to the loss….. and it’s drained to well below the minimum

That does seem odd. The other posts I've read always mention that small leaks tend to go unnoticed because the heat from the engine evaporates them, so there is no evidence. Maybe a UV dye testing kit is the way to go, to at least narrow the search.

[GlynH]

I had an unexplained coolant loss earlier this year with no sign of a leak anywhere.

Done a pressure test and it was losing pressure but very, very slowly.

I was expecting the worst but then decided to remove the undertray, checked the following morning and sure enough there was a slight sign of pooling adjacent to the front offside wheel arch.

Removed the wheel arch liner and there are a couple of aluminium cooling pipes behind it and one had a pinhole in it.

Done a temporary repair by splitting a piece of rubber hose and clamping it around the pipe where the pinhole was.

Sure enough the leak stopped which was a huge relief as I was worried it may have been head gaskets!

Ordered the wrong pipe - I believe it is listed under HVAC and not cooling and once replaced the coolant loss stopped completely.

Hope that helps?

-=Glyn=-

[monkeyboyuk]

Cheers glyn,

Originally Posted by GlynH

I had an unexplained coolant loss earlier this year with no sign of a leak anywhere.

Done a pressure test and it was losing pressure but very, very slowly.

I was expecting the worst but then decided to remove the undertray, checked the following morning and sure enough there was a slight sign of pooling adjacent to the front offside wheel arch.

Removed the wheel arch liner and there are a couple of aluminium cooling pipes behind it and one had a pinhole in it.

Done a temporary repair by splitting a piece of rubber hose and clamping it around the pipe where the pinhole was.

Sure enough the leak stopped which was a huge relief as I was worried it may have been head gaskets!

Ordered the wrong pipe - I believe it is listed under HVAC and not cooling and once replaced the coolant loss stopped completely.

Hope that helps?

-=Glyn=-